Hi,
Ive an old audi 80 tdi 1.9 (1995) with 175,000 mile on her, just passed another mot without a penny spent. I love this car!
I have noticed a missing in her at low revs in 4th and 5th gear. feels just like a petrol car running off 1 plug. It goes away again when i up the revs or go down a gear. Apart from this she drives perfectly, but its getting on my nerves. Ive added injection cleaner but no change. Any suggestions would be very gratefully appreciated.

 

Connect it to computer and check fault codes, it could be air flowmeter, N75 valve etc. You will know the reason if you check fault codes and engine parameters on dioagnostic computer